I have an underwater microphone "hydrophone" that should run on 12vDC and 45mA. Except that when I run it off of my power supply, it is wanting to draw around 3Amps of current at the 12volts. The three power wires are (+, -, and shield) and are correspondingly connected to the power supply's terminals (+, -, ground). This maybe the most retarded question ever but should I be getting continuity between the (+ and -) wires of the power cable? The differential output is wired to an XLR connector going into a data acquisition system. I don't know why this is drawing so much amperage!? What could be causing this? Are there any short circuiting tests or grounding issues that I should look for? Thank you so much.